Of major concern when a fighter aircraft is disabled in the air, is ejecting the crewmembers safely. In fighter aircraft, the air crewmembers initiate the process of ejection by pulling on an ejection handle, squeezing an ejection handle or some similar device to initiate ejection. The canopy that encloses the air crewmembers inside the aircraft cockpit is first blown or cut away. Next, the seat ejects out of the aircraft by a ballistic catapult along guide rails and the seat and air crewmember sitting thereon begins to enter the windblast. After the seat separates from the guide rails, it is propelled clear of the aircraft by rocket motors. When the seat reaches a safe trajectory, a parachute deploys for returning the air crewmember to the earth. The seat is stripped from the aircrew member and falls back to earth.
The proper positioning of the air crewmember in his seat is necessary for a safe ejection from the airplane. Such a positioning is requires that the air crew member is correctly aligned in his seat and that his arms and legs are safety stowed. Many factors affect positioning such as the attitude of the plane, is it flying straight, level and upright or is it in some other position?
A system identified as Inflatable Body and Head Restraint System, "IBAHRS" has been proposed which provides a pair of inflatables inside the vertical harness that extends from the five point rotary buckle to each shoulder. IBAHRS is a passive system that automatically tightens the harness at the onset of the crash. The inflatable pretensions the straps and forces the occupant back against the seat. This action lessens the chances of the air crew member from striking cockpit objects during the emergency.
However, in fixed wing aircraft, there are systems which use a net-like device that come out from the seat and tends to keep the arms and maybe the legs close to the body. In this way, when the air crewmember clears the aircraft, the windblast will not cause his limbs to flail. Around the ankles of the air crewmember are "garter-like" restraints that are tethered to the seat. During normal flying, the air crewmember's legs are free to move around, but during ejection, the tethers are pulled tight pulling the legs against the seat. Later when the air crewmember leaves the seat, the tethers are cut and the legs are no longer secured to the seat.
The location of the ejection handle, typically between the crewmember's legs, is designed so that as the air crewmember pulls the handle, this forces his arms against his/her chest.